The postmortem characteristics of Pima Indians of the Gila River Indian Community are investigated so that findings in subjects with and without diabetes mellitus can be correlated with studies in living subjects. In particular, the histology of the pancreatic islets of Langerhans is being studied in detail to describe the changes that take place in diabetes. A major analyses of causes of death, based on death certificates, of all Gila River Indian Community residents dying since l970 has been undertaken. The age-adjusted mortality rates due to all causes were approximately twice the rates for the State of Arizona. Particularly high were rates of death due to trauma, infections, diabetes, respiratory diseases, alcoholism and cirrhosis. In women, the rate of death due to biliary carcinoma was over l3 times the state rate. During a random survey for the prevalence of gallstones in 1968, 307 Pima Indians without prior evidence of gallbladder disease had oral cholecystograms (OCG). Medical records of 294 of the subjects were reviewed in l983. Three cases of biliary carcinoma were found in 107 people with abnormal OCGs, and none were found in 160 with normal nor in 27 with uncertain OCG results. These findings are consistent with the hypothesis that gallstones are a risk factor for biliary carcinoma. The l5-year cumulative mortality rates were examined in relation to the OCG result. Age-sex-adjusted mortality from all causes was 66% higher in those with abnormal than in those with normal cholecystograms (p less than 0.0l). There were no deaths attributed to cholecystectomies. These findings suggest that silent gallstones are not a benign condition in Pima Indians, and may predispose subjects, especially Indian women, to biliary carcinoma.